With ideal environmental factors, the reproduction rate of bacteria is

a. somewhat slow

b. somewhat rapid

c. extremely slow

d. extremely variable

e. extremely rapid

The main environmental factors that affect microorganism growth include chemical inhibitors, oxygen, pH, nutrients, moisture, and ______.

a. food texture

b. time

c. temperature

d. cleaning agents

e. all the answer choices are correct

At freezing temperatures, most bacteria

a. grow rapidly

b. form endospores

c. stop growing, but are not dead

d. are not affected by the cold

e. are destroyed

E. coli cells die at temperatures below 6° C.

True/False

What defines the safe temperature ranges for storage of foods?

a. Cessation of growth at low temperatures

b. Cell death at high temperatures

c. Cessation of growth at low temperatures AND cell death at high temperature

d. Type of preservation chemicals available

e. Size of bacterial cells

Correctly place the steps in the commercial production of wine.

A. Fermentation: A specially selected strain of S. cerevisiae is added to ferment the must (red wines) or clear juices (white wines)

B. Bottling: The wine is clarified by filtration and then bottled

C. Settling: The fermented material is transferred to a settling tank so that the solids can be removed

D. Crushing: Grapes are crushed, and the resulting must (solids and juice) is collected

E. Aging: Red wines and some white wines are aged in oak barrels 

D. Crushing: Grapes are crushed, and the resulting must (solids and juice) is collected

A. Fermentation: A specially selected strain of S. cerevisiae is added to ferment the must (red wines) or clear juices (white wines)

C. Settling: The fermented material is transferred to a settling tank so that the solids can be removed

E. Aging: Red wines and some white wines are aged in oak barrels

B. Bottling: The wine is clarified by filtration and then bottled

Identify the steps that might occur leading to foodborne intoxications by S. aureus and C. botulinum.

A. A person ingests the toxin-containing food. Symptoms of botulism begin in 12 to 36 hours.

B. Pathogen endospores contaminate many different foods.

C. A person ingests the toxin-containing food, resulting in food poisoning symptoms in 4 to 6 hours.

D. Most bacteria that compete with pathogen are killed by booking or inhibited by salty conditions.

E. A food handler inadvertently transfers pathogen onto food.

F. Pathogen grows and produces toxin when food cools slowly or is stored at room temperature.

G. Endospores survive inadequate canning processes. Canned foods are anaerobic.

H. Surviving endospores germinate, grow, and produce toxin in canned foods 

Staphyococcus aureus:

D. Most bacteria that compete with pathogen are killed by booking or inhibited by salty conditions.

E. A food handler inadvertently transfers pathogen onto food.

F. Pathogen grows and produces toxin when food cools slowly or is stored at room temperature.

C. A person ingests the toxin-containing food, resulting in food poisoning symptoms in 4 to 6 hours.

Clostridium botulinum: 

B. Pathogen endospores contaminate many different foods.

G. Endospores survive inadequate canning processes. Canned foods are anaerobic.

H. Surviving endospores germinate, grow, and produce toxin in canned foods 

A. A person ingests the toxin-containing food. Symptoms of botulism begin in 12 to 36 hours.

Most bacteria require an a_w (water activity) above 0.90 for growth. Which of the following is likely to spoil quickest? 

a. pure water- aw 1.0

b. cakes- aw 0.70

c. fresh stew- aw 0.98

d. jam- aw 0.85

e. cheese- aw 0.80

Why is ham (a_w = 0.91) a common source of S. aureus food poisoning?

Check all that apply.

a. S. aureus is adapted for growth on salty surface

b. S. aureus can grow at aw 0.86

c. Ham is moister than most other foods

d. Ham has no preservatives in it

e. There are few other competitive bacteria on ham

. S. aureus is adapted for growth on salty surface

b. S. aureus can grow at aw 0.86

d. Ham has no preservatives in it

Which is true regarding scientific names?

Click all that apply.

a. Scientific names are italicized or underlined

b. The first letters of both the genus name and the species name should be capitalized

c. Genus names are commonly abbreviated

a. Scientific names are italicized or underlined

c. Genus names are commonly abbreviated

Consider the Human Microbiome Project begun in 2007. The term "microbiome" has which two overlapping meanings?

a. The microbial community itself.

b. The local environment in which an individual human lives.

c. The total genetic content of a microbial community.

d. The ecosystem in which humans live. 

a. The microbial community itself.

c. The total genetic content of a microbial community.

The study of matter is called:

a. material science

b. microbiology

c. chemistry

d. physics

Match the level of protein structure on the left with the characteristics on the right.

Primary/secondary/tertiary/quartenary

sequence of amino acids/overall three-dimensional shape of a folded polypeptide/shape that results from two or more polypeptide chains in a protein/repeated coiling (alpha-helix) or folding (beta-pleated sheet) in localized regions of a protein

primary- sequence of amino acids

secondary- epeated coiling (alpha-helix) or folding (beta-pleated sheet) in localized regions of a protein

tertiary- overall three-dimensional shape of a folded polypeptide

quartenary- hape that results from two or more polypeptide chains in a protein

Which of the following are components of a nucleotide?

Check all that apply.

a. chloride base

b. phosphate group

c. pentose sugar

d. nucleobase

e. hexose sugar

f. nitric acid

g. sulfate group

b. phosphate group

c. pentose sugar

d. nucleobase

DNA is a double-stranded helical structure; the backbone of each strand is a series of alternating __ and __ units.

a. sugar, phosphate

b. guanine; cytosine

c. sugar; adenine

d. ribose; phosphate

Organic compounds that contain relatively electronegative atoms such as __ and __ are likely to form hydrogen bonds.

Choose all that apply.

a. sodium

b. nitrogen

c. oxygen

d. sulfur

b. nitrogen

c. oxygen

If you interfere with a bacterium's ability to make a sex pilus, that bacterium will no longer be able to __

Choose all that apply

a. join another bacterium

b. cause a specific sexually-transmitted disease

c. use a specific mechanusm to transfer its DNA

a. join another bacterium

c. use a specific mechanusm to transfer its DNA

Compared to sporulation, the process of germination is __

a. about the same

b. longer

c. shorter

Brief exposure to which of the following triggers endospore germination?

a. Drying 

b. Moisture

c. Heat

How does a bright-field microscope form its image?

a. It transmits light are the specimen

b. It transmits light through a specimen

c. It reflects light from a specimen

Which of teh following are found in Gram-negative cells but not Gram-positive cells?

a. Cytoplasmic membrane

b. Teichoic acid

c. Peptidoglycan

d. outer membrane

Which is the general description of a medium used to support bacterial growth in a Petri dish?

a. It contains only agar because contact with the air will provide the rest of the nutrients

b. It may have very few nutrients, or it may have many different nutrients to support widely carying growth requirements

c. It contains only agar, which serves as a rich source of nutrients to support a diversity of microbial growth

d. It must contain all possible nutrients, so that all microbes can grow

e. It must have minimal nutrient content, so that microbes are force to manufacture their required nutrients

Consider different ways to count cells. Match up the categories or examples of approaches with the most appropriate descriptions.

Direct microscopic count/Flow cytometer/Plate count/Membrane filtration/Most probable number

A statistical estimation rather than a precise measurment of cell numbers/Good for concentrating dilute samples of cells/Time-consuming but technically simple, counts living cells only/Rapid, involves a thin chamber that holds a known volume atop a microscopic grid/Detects the scatter of a laser beam as bacteria pass through a narrow channel

Direct microscopic count- Rapid, involves a thin chamber that holds a known volume atop a microscopic grid

Flow cytometer- Detects the scatter of a laser beam as bacteria pass through a narrow channel

Plate count- Time-consuming but technically simple, counts living cells only

Membrane filtration- Good for concentrating dilute samples of cells

Most probable number- A statistical estimation rather than a precise measurment of cell numbers

The polysaccharide found in marine algae that is commonly used to solidify culture media is called__

a. starch

b. agar

c. peptone

d. gelatin

Consider interactions of mixed microbial communities. Match the description in the left column with those that best correlate with them in the right column.

Difficult to reproduce in the laboratory/Simpler to reproduce in the laboratory/Inhibit competitors/Nutrients for another microbe/Creation of low O2 microenvironment

Pure cultures/Production of metabolic wastes by one microbe/Consumption of O2 by aerobic growth/Synthesis of toxic compounds/Conditions in close microbial associations

Difficult to reproduce in the laboratory- Conditions in close microbial associations

Simpler to reproduce in the laboratory- Pure cultures

Inhibit competitors- Synthesis of toxic compounds

Nutrients for another microbe- Production of metabolic wastes by one microbe

Creation of low O2 microenvironment- Consumption of O2 by aerobic growth

In the laboratory, a liquid or solid __ provides nutruents for microbial growth.

a. agar

b. medium

c. broth

Put the following phases in order for a normal bacterial growth curve, starting with the first phase of growth and ending with the last phase of growth.

A. Exponential

B. Lag

C. Death

D. Stationary

B. Lag

A. Exponential

D. Stationary

C. Death

Thayer-Martin agar is used to isolate Neisseria gonorrhoeae, a fastidious pathogen, from clinical specimens. This medium is chocolate agar to which three or more antimicrobial drugs have been added to inhibit the growth of fungi, gram-positive bacteria, and gram-negative rods, but not most N. gonorrhoeae strains. Which terms describe Thayer-Martin medium?

Choose all that apply.

a. Differential

b. Complex

c. Selective

d. Chemical

b. Complex

c. Selective

Thayer-Martin agar is used to isolate Neisseria gonorrhoeae, a fastidious pathogen, from clinical specimens. This medium is chocolate agar to which three or more antimicrobial drugs have been added to inhibit the growth of fungi, gram-positive bacteria, and gram-negative rods, but not most N. gonorrhoeae strains. Which terms describe Thayer-Martin medium?

Choose all that apply.

a. Differential

b. Complex

c. Selective

d. Chemical

b. Complex

c. Selective

Spontaneous generation can be explained as

a. life arising from nothing

b. an alternative name for evolution

c. development of life over time

d. life arising from dead matter

Choose which of the following results Pasteur might have obtained if the broth in his swan-necked flask experiment had contained endospores.

a. The broth would become cloudy as soon as Pasteur boiled it

b. The result of the experiment would be the same as that reported initially by Pasteur

c. The broth would seem sterile after boiling but would soon develop bacterial growth

d. The broth would remain sterile after boiling, unless the flask was tilted

e. All of the choices are correct

f. None of the choices are correct

Which of the following could survive if there were no prokaryotes on the planet?

a. Your microbiology instructor

b. Your neighbor and her cat

c. An apple tree

d. Mushrooms

e. None of the above

Which of the following is found only in bacteria?

a. Peptidoglycan

b. Chlorophyll

c. DNA

d. Phospholipids

e. ATP

Which of the following statements about bacteria is FALSE?

a. It is not always possible to eliminate bacteria with antibiotics

b. Information gained from studying bacteria can be applied to other organisms

c. Bacteria are a cause of illness and death

d. Bacteria are a source of fixed nitrogen

e. As a group, bacteria are very well characterized

f. Bacteria are essential to other life forms

Which of the following are the six most common elements found in all living organisms like bacteria?

Choose all that apply

a. Carbon

b. Hydrogen

c. Nitrogen

d. Oxygen

e. Phosphorus

f. Sulfur

g. Sodium

h. Potassium

i. Chlorine

j. Helium

k. water

l. Mercury

a. Carbon

b. Hydrogen

c. Nitrogen

d. Oxygen

e. Phosphorus

f. Sulfur

During a scientific expedition to the Arctic, you are experiencing daytime temperatures that are a bit below 0°C. You are hoping to discover bacteria that can still multiply at this temperature. Where would you have the best chance of finding actively growing bacteria in this environment?

a. surface of snow

b. It will not be possible to find growing bacteria at freezing temperatures

c. Seawater

d. Fresh water

e. Solid ice

Choose all of the following statements that are true regarding enzymes.

a. Enzymes are biological catalysts

b. Enzymes help break covalent bonds at temperatures suitable to life

c. Enzymes are helpful, but they are not essential to life

d. Enzymes can be either organic or inorganic

e. Enzymes can position reactants for bond formation

a. Enzymes are biological catalysts

b. Enzymes help break covalent bonds at temperatures suitable to life

e. Enzymes can position reactants for bond formation

DNA takes the form of a double helix in which two antiparallel strands of nucleotides are held together by hydrogen bonds that form between the nucleobases. There are two hydrogen bonds between each A-T pair and three hydrogen bonds between each G-C pair. You can extract DNA from bacteria and measure the temperature at which the DNA strands separate as they are heated. From this, you can calculate the percent GC content of their DNA. Although research has since refuted the idea (L.D. Hurst and A.R. Merchant, Proc Biol Sci. Mar 7, 2001; 268(1466): 493—497), the "thermal adaptation hypothesis" proposed that high GC content might be an adaptive response to high temperature. If this hypothesis were true, which of the following bacteria do you predict would have the highest number of G-C pairs in their chromosome?

a. A psychotroph living in your refrigerator

b. Thermophiles living in a hot spring

c. A psychophile living in a glacier-fed lake in the Artic

d. A mesophile such as Bacillus subtilis found growing in soil

e. A human pathogen such as E. coli

You discover an agent that multiplies in plant cells and is composed of RNA but nothing else. This agent would be a ______.

a. prokaryote cell

b. virus

c. viroid

d. prion

e. eukaryote cell